1. Field of the Invention
The present invention relates to a brake structure of a band reel in a packing machine.
2. Description of the Related Art
In an automatic or semi-automatic banding packing machine, a band reel 1 having a long band B wound thereupon is provided in a packing machine body 2 as shown in FIG. 4. A tip of the band B led from the band reel 1 is fed to the packing machine body 2 side by the rotating force of a feed roller (not shown) or the like.
In addition, a brake arm 3 is typically provided in the vicinity of the band reel 1 and the band B is fed to the packing machine body 2 side through a guide roller 3a of the brake arm 3.
In such a packing machine, in the case in which, in one packing step, the band is completely fed from the band reel 1 and is to be then returned and tightened, the rotation of the band reel 1 should be stopped immediately. Otherwise, an extra band is loosened so that a slack portion of the led band hangs and twist and entanglement problems are caused in the vicinity of the guide roller 3a. 
It is conventional to stop the rotation of the band reel 1 immediately after the band is completely fed, by pushing a brake pad against the side surface of the band reel 1 to stop the rotation by means of the brake pad. It is also known to stop the rotation of the band reel 1 by urging a U-shaped brake belt 5 shown in FIG. 5, for example, against a brake pulley during braking, the brake pulley being attached to the peripheral surface of a reel shaft 4 pivotally supporting the band reel 1.
In the method using the brake pad, however, the force for stopping the rotation is small and the band reel 1 is rotated for a while even if a stop operation is started. In the method using the brake belt 5, moreover, there has been a problem in that the force for stopping the rotation is great but the braking is not stabilized if the intrusion of the V belt is poor.
In consideration of the above-mentioned circumstances, it is an object of the present invention to provide a brake structure of a band reel in a packing machine in which braking effects can be obtained reliably and responsiveness is excellent.
In order to achieve the above-mentioned object, the present invention provides a brake structure of a band reel in a packing machine which is provided on a reel shaft for being rotated integrally with a band reel,
wherein a brake arm having a coil spring portion provided on one of its ends and a band passing ring portion provided on the other end is mounted on one of ends of the reel shaft and
one of ends on a coil spring side in the brake arm is fastened to a fixed or stationary member such as a device frame,
the coil spring portion receives force in a direction of an increase in a diameter by force applied from the fed band to form a clearance between an outer periphery of the reel shaft and an inner periphery of the coil spring, when the band inserted through the passing ring portion of the brake arm is sent toward a packing machine body side, and
a diameter of the coil spring portion is reduced to closely engage an inner peripheral surface of the coil spring portion with an outer peripheral surface of the reel shaft, thereby stopping a rotation of the reel shaft by frictional force, when the force for feeding the band is released.
According to the present invention having such a structure, when the band feeding operation is ended, the rotation of the band reel can be stopped, and furthermore, the structure can be simplified.
According to the brake structure of the band reel in the packing machine in accordance with the present invention, if the force for leading out the band through the band feeding roller is released when the band is completely fed from the band reel, the diameter of the coil spring portion is reduced so that the rotation of the reel shaft can be stopped. Accordingly, the slack portion of the band can be prevented from hanging. In such a structure, moreover, only the coil spring is used. Therefore, the structure can be simplified and the responsiveness can also be enhanced.
These objects as well as other objects, features and advantages of the present invention will become more apparent to those skilled in the art from the following description with reference to the accompanying drawings.